AP2转录因子调节激素反应性乳腺癌中CRABPII的表达。

AP2 transcription factors regulate expression of CRABPII in hormone responsive breast carcinoma.

作者信息

McPherson Lisa A, Woodfield George W, Weigel Ronald J

机构信息

Department of Surgery, Stanford University, Stanford, California, USA.

出版信息

J Surg Res. 2007 Mar;138(1):71-8. doi: 10.1016/j.jss.2006.07.002. Epub 2006 Dec 20.

DOI:10.1016/j.jss.2006.07.002

PMID:17187826

Abstract

BACKGROUND

The AP2 transcription factor family is a set of developmentally regulated, retinoic acid (RA) inducible genes, which regulate expression of estrogen receptor-alpha (ERalpha) in breast carcinoma. We hypothesized that AP2 factors regulate a set of genes characteristic of the hormone responsive breast cancer phenotype. To better understand the role of AP2 factors in hormone responsive breast cancer, we sought to identify AP2-target genes in breast epithelial cells.

MATERIALS AND METHODS

Overexpression of AP2 factors was achieved in human mammary epithelial cells (HMECs) using adenoviral vectors. AP2 target genes were identified by comparative hybridization to cDNA microarrays containing 30,000 human genes. Expression patterns were confirmed by Northern and Western blot and by elimination of AP2 using siRNA. Potential regulatory elements in promoters of target genes were identified by DNase I hypersensitive site mapping.

RESULTS

Comparative cDNA microarray hybridization identified a set of genes induced by overexpression of AP2alpha and AP2gamma in HMECs. The up-regulation of cellular retinoic acid-binding protein 2 (CRABPII), EST-1, and ECM1 was induced by overexpression of AP2alpha, AP2gamma, or a chimeric AP2 factor in which the activation domain of AP2alpha was replaced by the activation domain of herpesvirus VP16. Interestingly, hormone unresponsive MDA-MB-231 cells were resistant to CRABPII induction by any of the AP2 factors. Elimination of AP2gamma in MCF7 cells resulted in a significant reduction in CRABPII expression. AP2alpha induced DNase I hypersensitive sites in the promoter of the CRABPII gene at -5000 bp, which corresponds to the site of action of RAR/RXR factors.

CONCLUSIONS

AP2 factors regulate CRABPII expression in HMECs and breast cancer cells and accounts for the associated expression of ERalpha and CRABPII in hormone responsive breast cancer. Because CRABPII mediates growth suppressive effects of RA in breast cancer, the data suggest that AP2 factors have the ability to mediate RA responsiveness through the regulation of CRABP II expression.

摘要

背景

AP2转录因子家族是一组受发育调控、视黄酸（RA）诱导的基因，其在乳腺癌中调节雌激素受体α（ERα）的表达。我们推测AP2因子调控一组具有激素反应性乳腺癌表型特征的基因。为了更好地理解AP2因子在激素反应性乳腺癌中的作用，我们试图在乳腺上皮细胞中鉴定AP2靶基因。

材料与方法

使用腺病毒载体在人乳腺上皮细胞（HMECs）中实现AP2因子的过表达。通过与包含30000个人类基因的cDNA微阵列进行比较杂交来鉴定AP2靶基因。通过Northern印迹和Western印迹以及使用小干扰RNA（siRNA）消除AP2来确认表达模式。通过DNase I超敏位点作图鉴定靶基因启动子中的潜在调控元件。

结果

比较cDNA微阵列杂交鉴定出一组在HMECs中由AP2α和AP2γ过表达诱导的基因。细胞视黄酸结合蛋白2（CRABPII）、EST-1和ECM1的上调是由AP2α、AP2γ或一种嵌合AP2因子（其中AP2α的激活结构域被疱疹病毒VP16的激活结构域取代）的过表达诱导的。有趣的是，激素无反应性的MDA-MB-231细胞对任何AP2因子诱导的CRABPII均有抗性。在MCF7细胞中消除AP2γ导致CRABPII表达显著降低。AP2α在CRABPII基因启动子-5000 bp处诱导了DNase I超敏位点，这与视黄酸受体/视黄醇X受体（RAR/RXR）因子的作用位点相对应。